Apparatus for vacuum forming hot top bottom rings

ABSTRACT

The method and apparatus for automatically forming a hot top bottom ring from a slurry containing a major portion of granular refractory material, minor portions of inorganic fibrous material and porous refractory material and a resinous binder. The apparatus includes a reservoir containing the slurry, a mold assembly, and a transfer mechanism for moving the mold assembly into and out of the slurry in the reservoir. The mold assembly includes an upper mold member and a lower mold member, the lower member being mounted for movement into engagement with and away from the upper mold member, and a vacuum system operatively connected to the mold assembly to draw the slurry from the reservoir into the mold assembly and to dewater the slurry during the movement of the mold assembly to a dryer screen. The fibrous bottom ring formed in the mold assembly is removed therefrom by the application of air under pressure to deposit the bottom ring on the dryer screen.

United States Patent Varrati 1 Feb. 29, 1972 [54] APPARATUS FOR VACUUMFORMING Primary Examiner-Robert D. Baldwin HOT T()P BOTTOM RINGSAttorney-Ronald E. Barry and James E. Nilles [72] Inventor: Anthony J.Varrati, Milwaukee, Wis. [57] ABSTRACT Assigneel Universal lefractoriesCorporation The method and apparatus for automatically forming a hot topwaukee, Wis. bottom ring from a slurry containing a major portion ofgranu- [22] Filed: July 20 1970 lar refractory material, minor portionsof inorganic fibrous material and porous refractory material and aresinous binder. [2i] Appl- No.1 56, The apparatus includes a reservoircontaining the slurry, a mold assembly, and a transfer mechanism formoving the mold [521 U 5 CL 164/160 264/87 assembly into and out of theslurry in the reservoir. The mold [511 mo B28b 1/26 assembly includes anupper mold member and a lower mold 58] Fieid 253 160 264/87 86 member,the lower member being mounted for movement into engagement with andaway from the upper mold member, and a vacuum system operativelyconnected to the mold assembly [56] References cued to draw the slurryfrom the reservoir into the mold assembly UNITED STATES PATENTS and todewater the slurry during the movement of the mold assembly to a dryerscreen. The fibrous bottom ring formed in 1,880,006 9/1932 Young..264/87 the mold bl i removed therefrom by the application of 2,73l,6991/1956 Dubbs ..264/87 X air undelpreSSm-e to deposit h bottom ring onthe dryer 3,449,207 6/1969 Modersohn. .264/86 X Screen 3,512,572 5/1970Ednell ..164/7 X 17 Claims, 9 Drawing Figures /00 64 i /02 u we E l s5676 78 I l a2 74 a4 g .32 e4 1 r 4 l 72) a I 5 l I l ll 4 l; l! l: fli lI h g l www SHEET 3 OF 4 PATENTEDFEBZS 1912 APPARATUS FOR VACUUM FORMINGHOT TOP BOTTOM RINGS BACKGROUND OF THE INVENTION l-Iot top bottom ringsof the type shown in Thiem Reissue Pat. No. Re 26,381 issued Apr. 23,I968 generally are formed July 22, 1969 and assigned to the sameassignee has resulted in the design of bottom rings of substantially thesame materials as used to form the fibrous insert panels. It has beenfound, however, that the difficulties of automating the formation ofbottom rings as experienced in the manufacture of the bottom ringsdisclosed in the Thiem reissue patent can be overcome when using thefibrous material.

SUMMARY OF THE INVENTION The apparatus of the present inventiontherefore provides for the automatic formation of fibrous hot top bottomrings from a slurry of granular refractory material, minor portions ofinorganic fibrous material and porous refractory material and a resinousbinder. This is accomplished by using a novel mold assembly having upperand lower mold sections or members which are adapted to be closed andimmersed in the slurry. The slurry is drawn into the mold assembly by avacuum which is drawn through the mold assembly as the assembly iswithdrawn from the slurry to dewater the slurry and form the fibrousbottom ring. It should be noted in this connection that the bottom ringis formed on the upper mold member, thereby assuring that the uppersurface of the bottom ring has the exact contour required for matingengagement with the hot top casing and the panel insert unit. In thisconnection, the fibrous bottom ring when placed in the hot top engagesthe bottom of the casing and acts as a support for the panel insertunit. The bottom ring is provided with a novel locating arrangementwherein it is only necessary to place the bottom ring in position on thecasing and it automatically locates itself with respect to the insertunit.

It is also within the contemplation of the present invention to form thebottom ring within a wiper ring, in such a way that the wiper ring issecured to the outer periphery of the bottom ring. The wiper ring has asmall back draft angle between the face leg and the base leg and isplaced on the lower mold member of the mold assembly at the start of thecycle of operation. As the slurry is drawn into the mold assembly, itwill fill the space between the face leg and base leg of the bottom ringand when dewatered will produce a tight fit around the outer peripheryof the bottom ring.

The mold assembly can be modified to form panel insert units for hottops and side boards for ingot molds. As modified, the mold assemblywill provide accurate dimensions for the insert panels and side boards.

Other objects and advantages will become apparent from the followingdetailed description when read in connection with the accompanyingdrawings.

THE DRAWINGS FIG. 1 is a front elevation view of the apparatus of thisinvention with a portion of the front wall broken away to show the moldassembly;

FIG. 2 is a top view of the apparatus showing the mold assembly in thereservoir;

FIG. 3 is an end view taken on line 3-3 of FIG. 1 showing the moldassembly in an open position below the level of the slur- FIG. 4 is aview similar to FIG. 3 with the upper mold member in a release positionand the lower mold member supported on a cam plate out of the path ofmotion of the upper mold member;

FIG. 5 is a view of the bottom ring formed by the present method andapparatus and supported on the dryer screen;

FIG. 6 is a fragmentary sectional view of a hot top showing the fibrousbottom ring of this invention in position below the casing and panelinsert unit of the hot top.

FIG. 7 is a sectional view of the mold assembly showing the cavitybetween the upper and lower mold members taken on line 7-7 of FIG. 1.

FIG. 8 is a section view taken on line 8-8 of FIG. 1 showing the moldassembly leveling arrangement and the lower mold section movingassembly.

FIG. 9 is a section view in elevation showing the vacuum waterseparating tank.

DESCRIPTION OF THE INVENTION A hot top bottom ring 10 formed by themethod and apparatus of the present invention is shown in cross sectionin FIG. 6 positioned on the bottom of a hot top casing 12 in a positionto support a panel insert liner unit 14. This is the general arrangementof the elements which make up a hot top as seen in copending applicationSer. No. 843,384. The bottom ring 10 is automatically located on thecasing by means of the configuration of the upper surface of the centerportion 16 of the bottom ring. In this respect, the bottom ring 10 ispro vided with an outer section 18, the upwardly inclined center portion16 having a locating surface 20, and an inwardly extending ledge 22. Thelocating surface 20 is provided at an angle substantially equal to theangle of the bottom surface of the casing 12 for mating engagementtherewith when the bottom ring 10 is placed on the casing 12. The ledge22 underlies the panel insert unit 14 and provides a support for theinsert liner unit 14 when the casing 12 is turned right side up.

It should also be noted that a wiper strip 24 is mounted on the outerperiphery of section 18 of the bottom ring and includes a base leg 26and a face leg 28 which meet at an acute angle. A wiper blade 30 extendsoutwardly from the upper portion of the face leg 28. As pointed out moreparticularly hereinafter, the acute angle between the base leg 26 andthe face leg 28 of the wiper strip assures positive engagement of thewiper strip 24 on the outer periphery of the fibrous bottom ring 10thereby preventing removal of the wiper strip 24 from the bottom ring.The wiper strip 24 can also be provided with indents in the face leg 28which become embedded in the fibrous material of the bottom ring.

The bottom ring 10 is formed from a slurry 32 which contains a majorportion of granular refractory material, 70-80 parts by weight; minorportions of porous refractory material, 10 parts by weight; andinorganic fibrous material, 12-15 parts by weight; and an organic bindersuch as phenolic or furan resin, 5-10 parts by weight. This compositionis combined with water in the ratio of 15 parts of dry composition to 75parts water to form the slurry. After the bottom ring 10 has been formedand dried, it should be heat resistant at temperatures below 800 F. andheat destructible at temperatures above l,400 F. The slurry issubstantially identical to the slurry disclosed in copending applicationSer. No. 843,5 84.

In accordance with the invention, the fibrous bottom ring 10 is formedby means of the automatic molding apparatus 34 which includes areservoir 36 and a mold assembly 38 mounted on a transfer mechanism 40for movement from the slurry 32 in the reservoir 36 to a discharge orrelease position over a dryer screen 42. The reservoir 36 is filled withthe slurry 32 and the mold assembly 38 immersed in the slurry 32. Meansare provided for drawing a vacuum in the mold assembly 38 to form thebottom ring 10 and to dewater the bottom ring formed in the moldassembly. The mold assembly 38 is moved or transferred from thereservoir 36 and opened to allow the bottom ring 10 to be released fromthe mold assembly 38 and deposited on a dryer screen 42.

More particularly, and referring to FIGS. 1, 2 and 3, the reservoir 38includes downwardly sloping bottom walls 44, vertical sidewalls 46, andend walls 48. The slurry 32 is fed to the reservoir 36 by means of avalve 49 provided in a conduit 50 connecting a holding tank 52 to thereservoir 36. The level of the slurry in the reservoir 36 is maintainedby means of a float operated switch 54 positioned within the reservoir36 and electrically connected to open the valve 49.

The mold assembly 38 is supported for movement from the reservoir 36 tothe dryer screen 42 by means of the transfer mechanism 40. In thisregard, the transfer mechanism 40 includes a pair of support arms 56secured to pivot shafts 58 which are pivotally mounted in bearingbrackets 60 located on the end walls 48. The shafts 58 are rotated bymeans of a drive mechanism 62 as described hereinafter. A hollowcylindrical tube or conduit 64 is pivotally mounted on the ends of thesupport arms 56 and includes a number of openings 66.

The fibrous bottom ring is formed in the mold assembly 38 (FIG. 1 and 7)which includes an upper mold member or section 68 and a lower moldmember or section 70. The upper section 68 includes a vacuum box 72secured to the tube 64 by a bracket 74. A screen 76 is connected to theinner and outer walls of the vacuum box 72 and is contoured to providethe upper surface for the bottom ring 10. The vacuum box 72 is connectedto the tube 64 by means of a number of hoses 78 connected to theopenings 66 in the tube 64 and to openings 82 provided in the fourcorners of the box 72.

The lower mold member 70 includes a closed box 84 having a screen 86soldered to the edges of the box 84 to define the contour for the undersurface of the bottom ring 10. A number of tubes 88 are provided throughthe box 84 and screen 86 to provide communication between the interiorof the mold assembly 38 and the slurry 32 in the reservoir 36 asdescribed more fully below. The lower mold member 70 is supported on ahollow support tube 90 having a number of holes 92. The lower box 84 isconnected to the holes 92 by means of a number of tubes 94.

Means are provided for moving the lower member or section 70 relative tothe upper mold section 68 to open the mold assembly 38 after forming thebottom ring 10. Such means is in the form of a support mechanism 96which includes the hollow support tube 90 and a pair of arms 98pivotally connected to piston and cylinder assemblies 100. Theassemblies 100 are mounted at each end of the vacuum tube or pipe 64. Inthis regard, the piston and cylinder assemblies 100 each include acylinder 102 and a piston rod 104 which extends vertically up ward fromthe cylinder 102. The arms 98 are pivotally connected to the piston rods104 by pins 106. On actuation of the piston and cylinder assemblies 100the lower mold member 70 will be moved into and out of engagement withthe upper mold member 68.

Means are provided for cross-connecting the piston rods 104 to assure aneven and more level movement of the lower mold section 70 intoengagement with the upper mold section 68. Such means is in the fonn ofa rack 108 provided at the end of the piston rod 104 and a cross rod 110having a gear 112 secured to each end. The cross rod 110 is rotatablymounted on brackets 114 mounted at each end of the tube 64. By thisarrangement, any unbalancing of forces between the piston and cylinderassemblies 1 10 will be transmitted from on assembly to the other by thecross rod 110. The piston and cylinder assemblies 100 are actuated byconnecting the cylinders 102 to an air pump 172 through air hoses 115and 116. The air is controlled by a valve 117 in line 1 15.

After the mold assembly 38 has been immersed in the slurry 32 andclosed, a vacuum is drawn in the assembly by means of a vacuum pump 118connected to a water separation tank 120 which is connected to the endof the tube 64 by means of a valve 122 and a flexible conduit 124 and tothe end of tube 90 by means of a valve 126 and a flexible conduit 128.The vacuum drawn in the tubes 64 and 90-draws water from the moldassembly 38 into a water separation tank 120.

In this regard, and referring to FIG. 9, the water separation tank 120includes a dry-type vacuum pump 118 connected to the top of the tank 120by conduit 132. The valves 122 and 126 are connected to the tank 120 bymeans of a conduit 134. Water that is drawn into the tank 120 willaccumulate in the bottom of the tank. This water is removed from thetank 120 by means of pumps 136 and 138 which are connected to the tankby pipes 140 and 142, respectively. A unique switch arrangement 144 isused to control the water pumps 136 and 138 to prevent damage to thevacuum pump 118. The switch arrangement includes a water' level stopswitch 146, a start switch 148, a safety switch 150, and a vacuum pumpcutoff switch 152. The stop switch 146 is electrically connected to bothpumps 136 and 138 to stop both pumps whenever the level of water in thetank drops below the switch 146. The start switch 148 is electricallyconnected to start the pump 136 whenever the level of the water in thetank 120 reaches the start switch 148. In the event of failure of. thepump 136,

the water level will rise to the safety switch 150 which is electricallyconnected to the pump 138, and will start the pump 138 to remove waterfrom the tank 120. In the event both pumps 136 and 138 fail to start,the water will rise to the cutoff switch 152 which is electricallyconnected to cut off vacuum pump 118, thereby preventing damage to thevacuum pump.

Means are provided, as shown in FIG. 4, for pivoting the lower moldassembly 70 out of the path of travel of the upper mold member 68 whenthe bottom ring 10 is to be released from the mold assembly 38 to thedryer screen 42. Such means is in the form of a pair of cam plates 154provided on each end of the reservoir 36 and a cam roller 156 pivotallymounted on each end of the support tube 90. The cam rollers 156 arepivotally mounted on plates 158 which extend radially outwardly from thetube 90 and are located in a position to engage the surface of the camplates 154. As the transfer mechanism 40 is pivoted out of the reservoir36 the rollers 156 will roll around the cam plates 154 pivoting thesupport arms 98 about the pivot pins 106 on brackets 114. The supportarms 98 are positively located with respect to the upper mold section 68on the return motion of the transfer mechanism 40 by means of slottedguide plates 160 secured to brackets 162 mounted on each end of thesupport tube 64 below the piston and cylinder assemblies 100.

Means are provided to maintain the upper mold member 68 in asubstantially horizontal relation in the movement from the reservoir 36to the dryer screen 42 as seen in FIGS. 3, 4 and 8. Such means is in thefonn of a first fixed sprocket 164 provided on the housing 60 at one endof the reservoir 36, a second sprocket 166 secured to one end of thetube 64 and a chain 168 connecting the sprockets 164 and 166. Onmovement of the pivot arms 56 about their pivot axes, the chain 168 willremain fixed rotating the sprocket 166 as well as tube 64. The sprockets164 and 166 have substantially equal diameters so that the tube 64 turnsthrough 180 moving from the reservoir to the dryer screen 42 and backinto the reservoir 36.

The fibrous hot top 10 formed in the upper mold section 72 is releasedtherefrom by means of an air pressure system 170 connected to theflexible conduit 124. The air system 170 includes an air pump 172connected to conduit 124 by a tube 174 and a flexible hose 176. Airflowis controlled by means of a solenoid valve 178 provided in tube 174. Airunder pressure is applied to the vacuum box 72 through tube 64 andconduit 78 with sufficient force to blow the fibrous bottom ring 10 ontothe dryer screen 42.

Means are provided for aiding in the separation of the lower moldsection 70 from the upper mold 68 after the bottom ring 10 has beenformed in the mold assembly 38. Such means is in the form of the airpressure system 170 which is connected to the tube 90 by tube 180 and ahose 182. Air pressure to tube 90 is controlled by a solenoid valve 184.Air pressure is applied to the tube 90 by opening valve 184 atapproximately the same time as the piston and cylinder assemblies 100are actuated to separate the mold sections 68 and 70. This small amountof air under pressure aids in releasing the bottom ring l0'from thelower mold section 74.

Means are provided for moving the transfer mechanism 40 from thereservoir 36 to the dryer screen 42. Such means is in the form of thedrive mechanism 62 which is connected to a reversing electric motor 186mounted at one end of the reservoir 36. The motor 186 includes amagnetic brake for positive stop and a drive sprocket 188 which isconnected to a sprocket 190 by chain 192. Drive sprocket 190 is mountedon the end of a drive shaft 194 journaled in bearings 196 provided oneach end of the reservoir 36. The motion of the drive shaft 194 istransferred to the pivot shafts 58 by means of sprockets 195 on thedrive shaft 194 which are connected to sprockets 198 on the pivot shafts58 by chains 200.

The cycle of operation of the apparatus is controlled by means of anumber of cams 202, 204, 206, and 208 provided on the end of one of theshafts 58 and a corresponding number of switches 210, 212, 214, and 216provided on the end of the reservoir 36. A pair of limit switches 218and 220 are provided on the bracket 114 for the piston and cylinderassemblies 100 and a number of timers are provided on one end of thereservoir 36 to control various functions in the cycle of operation.Electric wiring of the control circuit is well known and can be easilyset up from the following description of the cycle of operation.

The cycle of operation of the apparatus to automatically form a bottomring is as follows. The reservoir 36 is initially filled with the slurry32 and the level in the reservoir maintained by means of the floatcontrolled switch 54. At the start of the cycle of operation, the moldassembly 38 is suspended above the slurry in an open position. A wiperstrip 24 can be placed on the lower mold section 70 while in thisposition. The cycle is started by closing a manual start button to startthe motor 186 and lower the mold assembly 38 into the slurry 32 in theopen position. When the mold assembly 38 is fully immersed in the slurry32, the motor 186 is stopped by the cam 202 on the pivot shaft 58 whichopens a switch 210. This switch will also start a timer which runs forapproximately 5 seconds. This timer then actuates the valve 113 topressurize the piston and cylinder assemblies 100 to close the moldassembly 38. After the mold assembly has closed, the piston rod 104 willengage the limit switch 128 on the bracket 114 starting a vacuum timer,closing valve 113 and opening the two vacuum valves 122 and 126 to thetubes 64 and 90. The vacuum timer will run for approximately to seconds.The vacuum pump 118 will draw a vacuum in the upper and lower moldsections 68 and 70. Additional slurry 32 will also be drawn into themold assembly 38 through the tubes 88 in the lower mold member 70. Atthe end of the set time period, the vacuum timer will start the motor186 to move the mold assembly 38 out of the slurry 32 until cam 204opens switch 212 stopping the motor 186 and opening the valve 113 to thepiston and cylinder assemblies 100 to open the mold assembly 38. Afterthe mold assembly 38 has been completely opened, the piston rod 104 willengage the second limit switch 220 on the bracket 114 to close valve 113to the assemblies 100 and to start the operation of a dryer timer andopen vacuum valves 122. The dryer timer will operate for approximately20 seconds after which the dryer timer will close the vacuum valvesstopping vacuum drying of the bottom ring 10 in the upper mold member68. The dryer timer will start the motor 186 to move the mold assembly38 to the release position. When the mold assembly reaches the releaseposition, the cam 206 will open switch 214 stopping the motor 186 andenergizing the air valve 184 to pressurize tube 64 and force the bottomring 10 out of the upper mold section 68 onto the dryer screen 42.Opening of switch 214 also closes a circuit to a release timer whichcloses valve 184 after a period of 5 seconds and starts the motor 186 toreturn the mold assembly 38 to the start position. On reaching the startposition, the cam 216 will open the circuit to the motor 186 to stop themold assembly 38 in the suspended position over the slurry.

The slurry 32 in the reservoir 36 is continuously agitated whenever themold assembly 38 is immersed in the slurry to assure even distributionof the fibrous materials throughout the slurry. Agitation is provided bymeans of a number of pipes 222, 224, and 226 provided in the bottom ofthe reservoir 36. The pipes are connected to the air pressure system 170by a conduit 228 which is controlled by means of a valve 230 connectedto the manual control switch. Air under pressure is imparted to thepipes 222, 224 and 226 whenever the mold assembly 38 is immersed in theslurry. Each of the pipes includes a number of holes along each side toblow air against the bottom walls 44 of the reservoir 36 therebybubbling the fibrous material throughout the slurry 32. A similararrangement is provided in the holding tank and is actuated off of thefloat control switch 54 for the holding tank to commence agitationwhenever the level in the reservoir 36 starts to drop and prior to theactuation of the valve 49 which controls the flow of the slurry into thereservoir 36.

The mold assembly 38 can be modified to produce other types of fibrousheat insulating members for use in hot tops and ingot molds such asinsert panels for hot tops and side boards for ingot molds. This isaccomplished by forming the walls of the upper vacuum box and lowervacuum box in the shape of the insert panels and side boards andmounting filter screens in the boxes to form the inside and outsidesurface of the panels and side boards. Since the screens will be locateda predetermined distance apart, a very accurate thickness can beprovided in the panels.

I claim:

1. An apparatus for forming a hot top bottom ring and insert, sideboards or any type fiber form from a slurry containing a major portionof granular refractory material, minor portions of an inorganic fibrousmaterial, and a resinous binder, said apparatus including,

a reservoir for the slurry,

a mold assembly for forming the fiber form including an upper moldsection and a lower mold section means for moving said lower moldsection into and out of engagement with said upper mold section in saidreservoir,

means for drawing a vacuum in said mold assembly,

and means for transferring said upper mold section and said lower moldsection from said reservoir to a position for releasing the bottom ringfrom said mold assembly.

2. The apparatus according to claim 1 wherein said moving means includesa pair of pneumatic piston and cylinder assemblies mounted on saidtransferring means.

3. The apparatus according to claim 1 wherein said transferring meansincludes means for maintaining said mold assembly in a substantiallyhorizontal position in the movement from the reservoir to the releaseposition.

4. The apparatus according to claim 3 wherein said maintaining meansincludes a sprocket fixedly mounted on said assembly, a hollow tube forsupporting said mold assembly, a second sprocket secured to one end ofsaid tube, and a chain interconnecting said sprockets.

5. The apparatus according to claim 1 including means for pivoting saidlower mold section out the path of motion of said upper mold section.

6. The apparatus according to claim 5 wherein said pivoting meanscomprises a pair of cam plates positioned at each end of said reservoir,a pair of arms pivotally connected to said upper section and a pair ofcam rollers positioned to engage the cam plates on movement of said moldassembly from said slurry to said release position.

7. The apparatus according to claim 1 including means for applying airunder pressure to said upper mold section to release the bottom ringfrom said upper mold section.

8. An apparatus for forming a bottom ring from a slurry containing amajor portion of granular refractory material, and a minor portion ofinorganic fibrous material, the apparatus comprising,

a reservoir for the slurry,

means for maintaining a predetermined level of slurry within thereservoir, a mold assembly having an upper section an a lower section,means for moving said lower mold section into and out of engagement withsaid upper mold section in said reser- V011,

means for transferring said mold assembly from a position below thelevel of the slurry in the reservoir to a release position,

means for applying a vacuum to said upper mold section and said lowermold section when immersed in the slurry,

and means for applying air under pressure to said upper mold sectionwhen said upper mold section is in the release position.

9. The apparatus according to claim 8 wherein said transferring meansincludes means for maintaining said upper mold section in a horizontalposition in the movement from said reservoir to said release position.

10. The apparatus according to claim 8 including means for supportingsaid lower mold section on said transferring means for pivotal movementout of the path of said upper section.

11. The apparatus according to claim 9 including means for applying airunder pressure to said lower mold section prior to separating said lowersection from said upper mold section.

12. An apparatus for forming a hot top bottom ring, said apparatuscomprising,

a vacuum mold assembly including an upper mold section having a screenshaped to define the upper surface of the bottom ring, and a lower moldsection having a screen to define the lower surface of the bottom ring,

means for immersing said assembly in a slurry containing minor portionsof inorganic fibrous material and porous refractory material,

means for closing said upper mold section and said lower mold sectiontrap the slurry in the cavity formed between said screens,

said means for drawing a vacuum in said upper mold section and saidlower mold section.

13. The apparatus according to claim 12 including means for admittingadditional slurry into said cavity formed on clos ing said assembly.

14. The apparatus according to claim 12 including means on said lowermold section for retaining a bottom ring on the periphery of said lowermold section.

15. The apparatus according to claim [2 including means for agitatingthe slurry whenever said mold assembly is immersed therein.

16. An apparatus forming a fibrous heat insulating member for use in ahot top or ingot mold, said apparatus comprising a vacuum mold assemblyincluding an upper mold section having a screen shaped to define theupper surface of the member, and a lower mold section having a screen todefine the lower surface of the bottom ring,

means for immersing said assembly in a slurry containing a major portionof granular refractory material and minor portions of inorganic fibrousmaterial and porous refractory material,

means for closing said upper mold section and said lower mold section totrap the slurry in the cavity formed between said screens,

and means for drawing a vacuum in said upper mold section and said lowermold section.

17. The apparatus according to claim 16 including means for admittingadditional slurry into said cavity.

1. An apparatus for forming a hot top bottom ring and insert, sideboards or any type fiber form from a slurry containing a major portionof granular refractory material, minor portions of an inorganic fibrousmaterial, and a resinous binder, said apparatus including, a reservoirfor the slurry, a mold Assembly for forming the fiber form including anupper mold section and a lower mold section means for moving said lowermold section into and out of engagement with said upper mold section insaid reservoir, means for drawing a vacuum in said mold assembly, andmeans for transferring said upper mold section and said lower moldsection from said reservoir to a position for releasing the bottom ringfrom said mold assembly.
 2. The apparatus according to claim 1 whereinsaid moving means includes a pair of pneumatic piston and cylinderassemblies mounted on said transferring means.
 3. The apparatusaccording to claim 1 wherein said transferring means includes means formaintaining said mold assembly in a substantially horizontal position inthe movement from the reservoir to the release position.
 4. Theapparatus according to claim 3 wherein said maintaining means includes asprocket fixedly mounted on said assembly, a hollow tube for supportingsaid mold assembly, a second sprocket secured to one end of said tube,and a chain interconnecting said sprockets.
 5. The apparatus accordingto claim 1 including means for pivoting said lower mold section out thepath of motion of said upper mold section.
 6. The apparatus according toclaim 5 wherein said pivoting means comprises a pair of cam platespositioned at each end of said reservoir, a pair of arms pivotallyconnected to said upper section and a pair of cam rollers positioned toengage the cam plates on movement of said mold assembly from said slurryto said release position.
 7. The apparatus according to claim 1including means for applying air under pressure to said upper moldsection to release the bottom ring from said upper mold section.
 8. Anapparatus for forming a bottom ring from a slurry containing a majorportion of granular refractory material, and a minor portion ofinorganic fibrous material, the apparatus comprising, a reservoir forthe slurry, means for maintaining a predetermined level of slurry withinthe reservoir, a mold assembly having an upper section an a lowersection, means for moving said lower mold section into and out ofengagement with said upper mold section in said reservoir, means fortransferring said mold assembly from a position below the level of theslurry in the reservoir to a release position, means for applying avacuum to said upper mold section and said lower mold section whenimmersed in the slurry, and means for applying air under pressure tosaid upper mold section when said upper mold section is in the releaseposition.
 9. The apparatus according to claim 8 wherein saidtransferring means includes means for maintaining said upper moldsection in a horizontal position in the movement from said reservoir tosaid release position.
 10. The apparatus according to claim 8 includingmeans for supporting said lower mold section on said transferring meansfor pivotal movement out of the path of said upper section.
 11. Theapparatus according to claim 9 including means for applying air underpressure to said lower mold section prior to separating said lowersection from said upper mold section.
 12. An apparatus for forming a hottop bottom ring, said apparatus comprising, a vacuum mold assemblyincluding an upper mold section having a screen shaped to define theupper surface of the bottom ring, and a lower mold section having ascreen to define the lower surface of the bottom ring, means forimmersing said assembly in a slurry containing minor portions ofinorganic fibrous material and porous refractory material, means forclosing said upper mold section and said lower mold section trap theslurry in the cavity formed between said screens, said means for drawinga vacuum in said upper mold section and said lower mold section.
 13. Theapparatus according to claim 12 including means for admitting additionalslurry into said cavity formed on closing said assembly.
 14. Theapparatus accoRding to claim 12 including means on said lower moldsection for retaining a bottom ring on the periphery of said lower moldsection.
 15. The apparatus according to claim 12 including means foragitating the slurry whenever said mold assembly is immersed therein.16. An apparatus forming a fibrous heat insulating member for use in ahot top or ingot mold, said apparatus comprising a vacuum mold assemblyincluding an upper mold section having a screen shaped to define theupper surface of the member, and a lower mold section having a screen todefine the lower surface of the bottom ring, means for immersing saidassembly in a slurry containing a major portion of granular refractorymaterial and minor portions of inorganic fibrous material and porousrefractory material, means for closing said upper mold section and saidlower mold section to trap the slurry in the cavity formed between saidscreens, and means for drawing a vacuum in said upper mold section andsaid lower mold section.
 17. The apparatus according to claim 16including means for admitting additional slurry into said cavity.